The invention relates to a high pressure clamping device, in other words, a machine vice having a force intensifier. The invention relates in particular to a high pressure clamping device with a vice body, a fixed jaw arranged at one end of the vice body, a slide which is retained in a guide on the vice body and carries a jaw movable relative to the fixed jaw, a thrust block on the other end of the vice body for a tensioning drive of the movable jaw, which consists of a force intensifier and a threaded spindle, which is operable by means of a common crank, by which the threaded spindle engages in a spindle nut of the slide.
A mechanical high pressure clamping device of the afore-mentioned type is well known. For this conventional type of high pressure clamping device the threaded spindle and the force intensifier are generally arranged above the vice body and approximately in the centre plane of the two jaws. When mention is made of the terms "above" or "below" or "top" or "bottom" in relation to said machine vice or high pressure clamping device in the preceding and subsequent text, it is on the basis that the high pressure clamping device rests on a level base. Naturally, it is a possible alternative to fix, for example, the high pressure clamping device of this type on a vertical base whereby the relative position of the individual parts correspondingly alter, without this having any affect upon the invention.
An arrangement of the threaded spindle and the intensifier unit lying in the plane of both jaws considerably increases the constructional length of such high presusre clamping devices. The total constructional length comprises the space required for the jaws, the slide, the threaded spindle, the force intensifier, the thrust block, the sleeve handle for operating the intensifier, plus a suitable crank. Thus, there is an unfavourable relationship between the available clamping distance and the total constructional length, and, in addition there are often problems regarding accommodating the high pressure clamping device in the machine tools in question. The space requirement necessary can only be reduced marginally by, for example, the crank being designed as a detachable item and by the slide carrying the movable jaw basically surrounding the threaded spindle, whereupon the slide must be relatively long in order to ensure positive guidance of this jaw.
Attempts have been maade to keep dimensions as small as possible even for the design of the force intensifier which may be regarded as a slave unit, whereby the slave unit can, for example, be used in accordance with West German patent specification No. 23 08 175 or alteratively a slave unit of another construction, for example, an hydraulically operated slave unit. But even these attempts have restrictions.
For machine vices not employing a slave unit it is known to utilise a so-called bottom tensioning construction, by which the threaded spindle is arranged beneath the clamping face of the vice body. Such a construction is described, for example, in West German patent specification No. 12 78 965. The threaded spindle has its thrust block in the region of the fixed jaw, and in the clamping operation the movable jaw is drawn against the fixed jaw. In utilising a slave unit there is the difficulty here in that in the clamping position the clamping force would have to be transmitted via the rotating threaded spindle, which seems not to be feasible. However, with this known construction there is the advantage that in the clamping operation the front end of the movable jaw is held down, by which a spreading out of the jaws, or an acute angle between the jaws is prevented.